Which of the following best represents an adaption to increase Surface to volume ratio

Cells receive material such as food, minerals, and oxygen from the outside world through

Imagine an invertebrate that lives in an estuary where salinity varies cyclically with the tides. If this individual is able to adjust the salt concentration of it's body fluids, it's salt concentration will have

The vertebrate kidney helps to keep the acidity of the body fluids constant by varying the amount of hydrogen ions it secretes into the urine. You can confidently predict that this aspect of kidney function will be controlled by